Semantic Integration Portal

The Semantic Integration Portal is a demonstration of the potential capabilities of Semantic Web applications in a knowledge-rich context. Source data is taken from different online terrorist incident aggregators and marked up according to ontologies specific to those domains. Unlike other semantic web techniques, which scrape the internet for raw data and then mark-up against a standard ontology, the approach here is to allow each data source to have its own domain-specific ontology. This allows the data producers the opportunity to mark up their data in their own way, producing RDF data according to their own ontologies without the need to conform to a standard. A variety of semantic integration techniques can then be applied to these ontologies, both automatic and interactive, allowing data from both sets to be viewed in a suitable application, in this case the mspace browser. Future iterations of the semantic integration portal aim to introduce more automated ontology-mapping techniques, aligning data from a variety of diverse sources with less need for human intervention

GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2

We describe the observation of GW170104, a gravitational-wave signal produced by the coalescence of a pair of stellar-mass black holes. The signal was measured on January 4, 2017 at 10∶11:58.6 UTC by the twin advanced detectors of the Laser Interferometer Gravitational-Wave Observatory during their second observing run, with a network signal-to-noise ratio of 13 and a false alarm rate less than 1 in 70 000 years. The inferred component black hole masses are 31. 2 + 8.4 − 6.0 M ⊙ and 19. 4 + 5.3 − 5.9 M ⊙ (at the 90% credible level). The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, χ eff = − 0.1 2 + 0.21 − 0.30 . This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. The source luminosity distance is 88 0 + 450 − 390     Mpc corresponding to a redshift of z = 0.1 8 + 0.08 − 0.07 . We constrain the magnitude of modifications to the gravitational-wave dispersion relation and perform null tests of general relativity. Assuming that gravitons are dispersed in vacuum like massive particles, we bound the graviton mass to m g ≤ 7.7 × 10 − 23     eV / c 2 . In all cases, we find that GW170104 is consistent with general relativity

First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data

We report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100 Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7 [1/root Hz]. At the frequency of best strain sensitivity, near 100 Hz, we set 90% confidence upper limits of 1.8 x 10(-25). At the low end of our frequency range, 20 Hz, we achieve upper limits of 3.9 x 10(-24). At 55 Hz we can exclude sources with ellipticities greater than 10(-5) within 100 pc of Earth with fiducial value of the principal moment of inertia of 10(38) kg m(2)

Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO

During their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100 M ⊙, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93 Gpc−3yr−1 in comoving units at the 90% confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits

Semiometrics: producing a compositional view of influence

High-impact academic papers are not necessarily the most cited. For example,Einstein's 'Special Relativity' paper from 1905 received (and continues to receive)fewer citations from other papers than his 'Brownian Motion" paper of the sameyear, despite the former radically changing the course of an entire scientificdiscipline to a much greater extent. Similarly, 'impact' metrics using citation countalone are, it is argued, not adequate for determining the scientific influence ofpapers, authors or small groups of authors. Although valid, they remaincontroversial when used to determine influence of larger groups or journals. Whilethe term 'impact' has become closely linked to a journal's citation-based JournalImpact Factor score, this thesis uses the term 'influence' to describe the widereffectiveness of research, combining citation and metadata analysis to allow richercalculations to be performed over large-scale document networks. As a result, morequalitative influence ratings can be determined and a broader outlook on scientificdisciplines can be produced. These ratings are best applied using an ontology-baseddata source, allowing more efficient inference than under a traditional RDBMSsystem, and allowing easier integration between heterogeneous data sources. Thesemetrics, termed 'Semantic Bibliometrics' or 'Semiometrics', can be applied at avariety of levels of granularity, allowing a compositional framework for impact andinfluence analysis. This thesis describes the process of data preparation, systemsarchitecture, metric value and data integration for such a system, introducing novelapproaches at all four stages, thereby creating a working semiometrics system fordetermining influence at different semantic levels of granularity

Semiometrics: Applying Ontologies across Large-Scale Digital Libraries

As large-scale digital libraries become more available and complete, not to mention more numerous, it is clear there is a need for services that can draw together and perform inference calculations on the metadata produced. However, the traditional Relational Database Management System (RDBMS) model, while efficiently constructed and optimised for many business structures, does not necessarily cope well with issues of concurrent data updates and retrieval at the scale of hundreds of thousands of papers. At the same time the growth of RDF and the increasing interest in Semantic Web technologies perhaps begins to present a viable alternative at a scalable, practical level. This paper considers a specific application of large-scale metadata analysis and conducts scalability tests using real-world data. It concludes that RDF technologies are both a scalable and performance-realistic alternative to traditional RDBMS approaches. It also shows that for relationship-based queries on large-scale metadata stores, RDF technologies can significantly out-perform traditional RDBMS approaches by allowing both retrieval and updating of data in a timely manner

Also By The Same Author: AKTiveAuthor, a Citation Graph Approach to Name Disambiguation

The desire for definitive data and the semantic web drive for inference over heterogeneous data sources requires co-reference resolution to be performed on those data. In particular, name disambiguation is required to allow accurate publication lists, citation counts and impact measures to be determined. This paper describes a graph-based approach to author disambiguation on large-scale citation networks. Using self-citation, co-authorship and document source analyses, AKTiveAuthor clusters papers, achieving precision of 0.997 and recall of 0.818 over a test group of eight surname clusters

Semantic Technologies and Enhanced Situation Awareness

Situation awareness is a critical element of military decision superiority in a wide variety of operational contexts. Improved situation awareness can benefit operational effectiveness by facilitating the planning process, improving the quality and timeliness of decisions, and providing better feedback about the strategic and tactical consequences of military actions. The military coalition environment presents a number of challenges to situation awareness research; not only in terms of the technical approaches used to enhance situation awareness, but also in terms of the models and conceptual frameworks used to analyse situation awareness. This paper outlines an approach to enhancing situation awareness that is grounded in the use of Semantic Web technologies. We describe the challenges to both individual and team situation awareness presented by coalition military environments, and we discuss ways in which semantic technologies might be used to address these challenges. We suggest that an approach featuring domain ontologies, reasoning capabilities, semantic queries and semantic integration techniques provides the basis for an integrated framework for improving situation awareness in military coalition contexts. We provide an example of our approach in the form of the InfoGlue framework for adaptive, context-aware information retrieval